feat: declare the SNMP health OIDs instead of collecting them (0.2.0)

netgear_smart no longer collects over SNMP. SNMP_HEALTH_PROFILE states
where the switch publishes uptime (standard sysUpTime), memory (total
and free in KiB) and CPU (a text value whose five-second figure
counts); the application polls and computes (napalm-device-types
docs/STRUCTURE.md).

Interface counters now come from the 64-bit ifXTable where the switch
has it, as the application reads them for every device.

tests/unit/test_snmp_profile.py

@@ -0,0 +1,33 @@
+"""The switch's SNMP health OIDs, declared as data (napalm-device-types docs/STRUCTURE.md).
+
+The driver does not collect over SNMP; the application polls with this profile.
+"""
+
+import re
+
+from napalm_netgear.netgear_smart import NetgearSmartDriver
+
+PROFILE = NetgearSmartDriver.SNMP_HEALTH_PROFILE
+
+
+def test_the_driver_does_not_collect_itself():
+    assert "get_health_metrics" not in vars(NetgearSmartDriver)
+
+
+def test_uptime_from_the_standard_sysuptime():
+    assert PROFILE["uptime"] == {"oids": ["1.3.6.1.2.1.1.3.0"]}
+
+
+def test_memory_from_total_and_free_in_kib():
+    assert PROFILE["memory"] == {
+        "total": {"oids": ["1.3.6.1.4.1.4526.100.1.1.4.2.0"]},
+        "free": {"oids": ["1.3.6.1.4.1.4526.100.1.1.4.1.0"]},
+        "unit": "KiB",
+    }
+
+
+def test_cpu_is_the_five_second_figure_in_a_text_value():
+    cpu = PROFILE["cpu"]
+    assert cpu["oids"] == ["1.3.6.1.4.1.4526.100.1.1.4.9.0"]
+    text = "    5 Secs ( 3.2%)   60 Secs ( 4.1%)  300 Secs ( 2.0%)"
+    assert re.search(cpu["pattern"], text).group(1) == "3.2"